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    <meta charset="UTF-8">
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    <title>Document</title>
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    <script>
        var str = 'js  89 is good ,js study easy 78';
        // 1、replace
        console.log(str.replace(/\d\d/g,'php'));
        // 2、search
        console.log(str.search(/\d\d/))
        // 3、match
        console.log(str.match(/\d\d/))
    </script>
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